Selective marker gene is an effective tool used for the selection of positive callus of plant transformation.Currently

almost all of selective marker genes are driven by constitutive promoters.Although these promoters are widely used for plants transformation

the constitutive expressions of marker gene in transgenic plants have potential safety concern.To solve this problem

we cloned a callus-specific promoter from rice CP（Cyctein protease） gene.Through transgenic approach using gus as a reporter gene

it was easy to find that CP promoter was specifically expressed in callus

but not in roots

stem

leaves or any other tissues.So we designated it as a Callus-specific Promoter（CSP）.To improve the selective efficiency

CP promoter was fused to a codon optimized selective marker gene hpt and the selective efficiency of CP promoter was obviously improved.The transformation efficiency and positive calli resisted to hpt gene were nearly the same as that of pCAMBIA1301

which the marker gene hpt was driven by 35S promoter.Our results established a selective marker system that utilized CP promoter mediated hpt gene expression.This system has independent intellectual property and provides a new way for the security guarantees of transgenic plants.